Alfred Day Hershey

Hershey, Alfred Day, 1908–1997, American microbiologist, b. Owosso, Mich., Ph.D., Michigan State College (now Michigan State Univ.), 1934. Hershey was a professor at the Washington Univ. School of Medicine (1934–50), then joined the Carnegie Institution of Washington, Cold Spring Harbor, N.Y. He was director of the genetics research unit there from 1962 until he retired in 1974. In 1969 he shared the Nobel Prize in physiology or medicine with Max Delbrück and Salvador Luria for parallel work that led to new knowledge about the replication mechanism and genetic structure of viruses. Beginning in 1940, the three became interested in using bacteriophages, a group of viruses that destroy bacteria, to study self-replication, mutation, and other fundamental life processes. Hershey built on Delbrück's finding that viruses infecting the same cell showed an unexpected interaction and demonstrated that this phenomenon was the result of genetic recombination and, further, that it could be used to construct the genetic map of viruses. Collectively, the work of the three made significant contributions to the discipline of virology and to the progress of molecular biology.